AB0103 SITE SPECIFICITY OF RHEUMATOID ARTHRITIS INFLAMMATION: A SECONDARY ANALYSIS OF BIOPSIES FROM RADIAL AND ULNAR ASPECTS OF MCP JOINTS
Authors: K. Skovsgaard Itenov, N. Søe, E. M. Bartels, H. Bliddal, M. Andersen
Journal: Annals of the Rheumatic Diseases (2022)

Background Ulnar drift is a common complication of Rheumatoid Arthritis (RA) (1,2). There is no clear consensus regarding the etiology of the hand deformity. Observations from corrective hand surgery and other studies have noted more pronounced inflammation in the radial site of the MCP-joints (3,4). This could partly explain the pathophysiology behind the ulnar deviation. Objectives To determine if there is more pronounced inflammation, measured by increased CD-68 expression (5) and Krenn-synovitis score (6), at the radial side of the MCP joints when compared to the ulnar side, in patients with verified RA. Methods We included RA patients from a previous study who had biopsies taken from the most affected joints based on clinical examination and ultrasound (7). Twenty-nine PIP-, MCP- and wrist-joints were biopsied. Biopsies from the MCP-joints were taken from the dorso-ulnar and dorso-radial concavity. Inflammation was graded by the Krenn-synovitis score (0-9) and the density of CD-68-positive cells (%). The difference between radial and ulnar joint inflammation was calculated by paired t-test. P-value &lt;0.05 was considered statistically significant. Results In 8 patients biopsies were taken from both the ulnar and the radial site of the same MCP-joint. The mean difference in inflammation on the radial and ulnar site of MCP-joints was based on differences in CD-68 density: 0,67% (95%-CI -4,77 to 6,10; P = 0,77) (Figure 1) and Krenn-score: 0,83 (95%-CI -1,31 to 2,98; P = 0,36), respectively. Figure 1. Paired data on CD-68 percentage in radial and ulnar sites Conclusion There was no difference in concentration of inflammatory cells or overall synovial pathology between the radial and ulnar site of MCP-joints in RA patients. The impression of a more pronounced inflamed synovium on the radial site of MCP joints, as observed during surgery, does not seem to arise from an immunological preference, but rather to be linked to a larger synovial volume. References [1]Wise KS: The anatomy of the metacarpo-phalangeal joints, with observations of the aetiology of ulnar drift. J. Bone Joint Surg. Br. 1975; 57:485–90 [2]Johnsson PM, Eberhardt K: Hand deformities are important signs of disease severity in patients with early rheumatoid arthritis. Rheumatology 2009; 48:1398–1401 [3]Philpott H.T. Synovial tissue perivascular edema is associated with altered gait patterns in patients with knee osteoarthritis, Osteoarthritis and Cartilage . 2022; 30(1): 42-51 [4]Tan AL, Tanner SF, Conaghan PG, et al.: Role of metacarpophalangeal joint anatomic factors in the distribution of synovitis and bone erosion in early rheumatoid arthritis. Arthritis Rheum. 2003; 48:1214–22 [5]Zhang X.-P: Addition of Fibroblast-Stromal Cell Markers to Immune Synovium Pathotypes Better Predicts Radiographic Progression at 1 Year in Active Rheumatoid Arthritis, Frontiers in Immunology 2021; 12: 778480 [6]Krenn V, Morawietz L, Burmester G-R, et al.: Synovitis score: discrimination between chronic low-grade and high-grade synovitis. Histopathology 2006; 49:358–364 [7]Andersen M, Ellegaard K, Hebsgaard JB, et al.: Ultrasound colour Doppler is associated with synovial pathology in biopsies from hand joints in rheumatoid arthritis patients: a cross-sectional study. Ann. Rheum. Dis. 2014; 73:678–683 Acknowledgements The authors would like to thank the study participants as well as Inger Wätjen, Eva Littrup Andersen, Mette Okkels, Jette Møller Frøsig and Suzi Høeg Madsen for technical assistance. I have no acknowledgements to declare. Disclosure of Interests Katrine Skovsgaard Itenov: None declared, Niels Søe: None declared, Else Marie Bartels: None declared, Henning Bliddal: None declared, Martin Andersen Grant/research support from: The primary study was supported by unrestricted grants from Novo Nordisk, Employee of: Was employed at Novo Nordisk A/S during the conduction of the study.